library/src/main/java/org/apache/apex/malhar/lib/appdata/schemas/SchemaUtils.java - apex-malhar - Git at Google

 /**
  * Licensed to the Apache Software Foundation (ASF) under one
  * or more contributor license agreements.  See the NOTICE file
  * distributed with this work for additional information
  * regarding copyright ownership.  The ASF licenses this file
  * to you under the Apache License, Version 2.0 (the
  * "License"); you may not use this file except in compliance
  * with the License.  You may obtain a copy of the License at
  *
  *   http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing,
  * software distributed under the License is distributed on an
  * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
  * KIND, either express or implied.  See the License for the
  * specific language governing permissions and limitations
  * under the License.
  */
 package org.apache.apex.malhar.lib.appdata.schemas;

 import java.io.IOException;
 import java.io.InputStream;
 import java.io.StringWriter;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;

 import org.codehaus.jettison.json.JSONArray;
 import org.codehaus.jettison.json.JSONException;
 import org.codehaus.jettison.json.JSONObject;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;

 import org.apache.commons.io.IOUtils;

 import com.google.common.base.Preconditions;
 import com.google.common.collect.Lists;
 import com.google.common.collect.Maps;
 import com.google.common.collect.Sets;

 /**
  * This class holds utility methods for processing JSON.
  * @since 3.0.0
  */
 public class SchemaUtils
 {
   public static final String FIELD_TAGS = "tags";

   /**
    * This constructor should not be used.
    */
   private SchemaUtils()
   {
     //Do nothing
   }

   /**
    * This is a utility method which loads the contents of a resource file into a string.
    * @param resource The resource file whose contents need to be loaded.
    * @return The contents of the specified resource file.
    */
   public static String jarResourceFileToString(String resource)
   {
     StringWriter stringWriter = new StringWriter();
     try {
       InputStream is = SchemaUtils.class.getClassLoader().getResourceAsStream(resource);
       Preconditions.checkArgument(is != null, resource + " could not be found in the resources.");

       IOUtils.copy(is, stringWriter);
     } catch (IOException ex) {
       throw new RuntimeException(ex);
     }
     return stringWriter.toString();
   }

   /**
    * This is a utility method that loads the contents of the given input stream into a string.
    * @param inputStream The input stream to read from.
    * @return The contents of the given input stream as a String.
    */
   public static String inputStreamToString(InputStream inputStream)
   {
     StringWriter stringWriter = new StringWriter();

     try {
       IOUtils.copy(inputStream, stringWriter);
     } catch (IOException ex) {
       throw new RuntimeException(ex);
     }

     return stringWriter.toString();
   }

   /**
    * This is a utility method to check that the given JSONObject has the given keys.
    * @param jo The {@link JSONObject} to check.
    * @param fields The keys in the {@link JSONObject} to check.
    * @return True if the given {@link JSONObject} contains all the given keys. False otherwise.
    */
   public static boolean checkValidKeys(JSONObject jo, Fields fields)
   {
     @SuppressWarnings("unchecked")
     Set<String> fieldSet = fields.getFields();
     Set<String> jsonKeys = getSetOfJSONKeys(jo);

     return jsonKeys.containsAll(fieldSet);
   }

   /**
    * This is a utility method to check that the given JSONObject has the given keys.
    * It throws an {@link IllegalArgumentException} if it doesn't contain all the given keys.
    * @param jo The {@link JSONObject} to check.
    * @param fields The keys in the {@link JSONObject} to check.
    */
   public static void checkValidKeysEx(JSONObject jo, Fields fields)
   {
     @SuppressWarnings("unchecked")
     Set<String> fieldSet = fields.getFields();
     Set<String> jsonKeys = getSetOfJSONKeys(jo);

     if (!jsonKeys.containsAll(fieldSet)) {

       throw new IllegalArgumentException("The given set of keys " + fieldSet
           + " doesn't equal the set of keys in the json " + jsonKeys);
     }
   }

   /**
    * This is a utility method to check that the given JSONObject has the given keys.
    * @param jo The {@link JSONObject} to check.
    * @param fieldsCollection The keys in the {@link JSONObject} to check.
    * @return True if the given {@link JSONObject} contains all the given keys. False otherwise.
    */
   public static boolean checkValidKeys(JSONObject jo, Collection<Fields> fieldsCollection)
   {
     return checkValidKeysHelper(jo, fieldsCollection);
   }

   private static boolean checkValidKeysHelper(JSONObject jo, Collection<Fields> fieldsCollection)
   {
     for (Fields fields: fieldsCollection) {
       LOG.debug("Checking keys: {}", fields);
       if (checkValidKeys(jo, fields)) {
         return true;
       }
     }

     LOG.error("The first level of keys in the provided JSON {} do not match any of the " + "valid keysets {}",
         getSetOfJSONKeys(jo), fieldsCollection);
     return false;
   }

   public static boolean checkValidKeys(JSONObject jo, List<Fields> fieldsCollection)
   {
     return checkValidKeysHelper(jo, fieldsCollection);
   }

   /**
    * This is a utility method to check that the given JSONObject has the given keys.
    * It throws an {@link IllegalArgumentException} if it doesn't contain all the given keys.
    * @param jo The {@link JSONObject} to check.
    * @param fieldsCollection The keys in the {@link JSONObject} to check.
    * @return True if the given {@link JSONObject} contains all the given keys. False otherwise.
    */
   public static boolean checkValidKeysEx(JSONObject jo, Collection<Fields> fieldsCollection)
   {
     return checkValidKeysExHelper(jo, fieldsCollection);
   }

   public static boolean checkValidKeysExHelper(JSONObject jo, Collection<Fields> fieldsCollection)
   {
     for (Fields fields: fieldsCollection) {
       if (checkValidKeys(jo, fields)) {
         return true;
       }
     }

     Set<String> keys = getSetOfJSONKeys(jo);

     throw new IllegalArgumentException("The given json object has an invalid set of keys: " + keys
         + "\nOne of the following key combinations was expected:\n" + fieldsCollection);
   }

   public static boolean checkValidKeysEx(JSONObject jo, List<Fields> fieldsCollection)
   {
     return checkValidKeysExHelper(jo,
                                   fieldsCollection);
   }

   public static Set<String> getSetOfJSONKeys(JSONObject jo)
   {
     @SuppressWarnings("unchecked")
     Iterator<String> keyIterator = jo.keys();
     Set<String> keySet = Sets.newHashSet();

     while (keyIterator.hasNext()) {
       keySet.add(keyIterator.next());
     }

     return keySet;
   }

   public static Map<String, String> convertFieldToType(Map<String, Type> fieldToType)
   {
     Map<String, String> fieldToTypeString = Maps.newHashMap();

     for (Map.Entry<String, Type> entry : fieldToType.entrySet()) {
       String field = entry.getKey();
       String typeString = entry.getValue().name();

       fieldToTypeString.put(field, typeString);
     }

     return fieldToTypeString;
   }

   public static JSONArray findFirstKeyJSONArray(JSONObject jo, String key)
   {
     if (jo.has(key)) {
       try {
         JSONArray jsonArray = jo.getJSONArray(key);
         return jsonArray;
       } catch (JSONException ex) {
         throw new RuntimeException(ex);
       }
     }

     @SuppressWarnings("unchecked")
     Iterator<String> keyIterator = jo.keys();

     while (keyIterator.hasNext()) {
       String childKey = keyIterator.next();

       JSONArray childJa = null;

       try {
         childJa = jo.getJSONArray(childKey);
       } catch (JSONException ex) {
         //Do nothing
       }

       if (childJa != null) {
         JSONArray result = findFirstKeyJSONArray(childJa, key);

         if (result != null) {
           return result;
         }

         continue;
       }

       JSONObject childJo = null;

       try {
         childJo = jo.getJSONObject(childKey);
       } catch (JSONException ex) {
         //Do nothing
       }

       if (childJo != null) {
         JSONArray result = findFirstKeyJSONArray(childJo, key);

         if (result != null) {
           return result;
         }
       }
     }

     return null;
   }

   public static JSONArray findFirstKeyJSONArray(JSONArray ja, String key)
   {
     for (int index = 0; index < ja.length(); index++) {
       JSONArray childJa = null;

       try {
         childJa = ja.getJSONArray(index);
       } catch (JSONException ex) {
         //Do nothing
       }

       if (childJa != null) {
         JSONArray result = findFirstKeyJSONArray(childJa, key);

         if (result != null) {
           return result;
         }

         continue;
       }

       JSONObject childJo = null;

       try {
         childJo = ja.getJSONObject(index);
       } catch (JSONException ex) {
         //Do nothing
       }

       if (childJo != null) {
         JSONArray result = findFirstKeyJSONArray(childJo, key);

         if (result != null) {
           return result;
         }
       }
     }

     return null;
   }

   public static JSONObject findFirstKeyJSONObject(JSONObject jo, String key)
   {
     if (jo.has(key)) {
       try {
         JSONObject jsonObject = jo.getJSONObject(key);
         return jsonObject;
       } catch (JSONException ex) {
         throw new RuntimeException(ex);
       }
     }

     @SuppressWarnings("unchecked")
     Iterator<String> keyIterator = jo.keys();

     while (keyIterator.hasNext()) {
       String childKey = keyIterator.next();

       JSONArray childJa = null;

       try {
         childJa = jo.getJSONArray(childKey);
       } catch (JSONException ex) {
         //Do nothing
       }

       if (childJa != null) {
         JSONObject result = findFirstKeyJSONObject(childJa, key);

         if (result != null) {
           return result;
         }

         continue;
       }

       JSONObject childJo = null;

       try {
         childJo = jo.getJSONObject(childKey);
       } catch (JSONException ex) {
         //Do nothing
       }

       if (childJo != null) {
         JSONObject result = findFirstKeyJSONObject(childJo, key);

         if (result != null) {
           return result;
         }
       }
     }

     return null;
   }

   public static JSONObject findFirstKeyJSONObject(JSONArray ja, String key)
   {
     for (int index = 0; index < ja.length(); index++) {
       JSONArray childJa = null;

       try {
         childJa = ja.getJSONArray(index);
       } catch (JSONException ex) {
         //Do nothing
       }

       if (childJa != null) {
         JSONObject result = findFirstKeyJSONObject(childJa, key);

         if (result != null) {
           return result;
         }

         continue;
       }

       JSONObject childJo = null;

       try {
         childJo = ja.getJSONObject(index);
       } catch (JSONException ex) {
         //Do nothing
       }

       if (childJo != null) {
         JSONObject result = findFirstKeyJSONObject(childJo, key);

         if (result != null) {
           return result;
         }
       }
     }

     return null;
   }

   /**
    * Converts the given JSONObject into a {@link Map}.
    * @param jo The {@link JSONObject} to convert.
    * @return The converted {@link JSONObject}.
    */
   public static Map<String, String> extractMap(JSONObject jo)
   {
     Map<String, String> resultMap = Maps.newHashMap();
     @SuppressWarnings("unchecked")
     Iterator<String> keyIterator = jo.keys();

     while (keyIterator.hasNext()) {
       String key = keyIterator.next();
       String value;

       try {
         value = jo.getString(key);
       } catch (JSONException ex) {
         throw new RuntimeException(ex);
       }

       resultMap.put(key, value);
     }

     return resultMap;
   }

   /**
    * This is a utility method which creates a {@link JSONObject} out of the given map.
    * @param map The map to convert into a {@link JSONObject}.
    * @return The converted map.
    */
   public static JSONObject createJSONObject(Map<String, String> map)
   {
     JSONObject jo = new JSONObject();

     for (Map.Entry<String, String> entry : map.entrySet()) {
       String key = entry.getKey();
       String value = entry.getValue();

       try {
         jo.put(key, value);
       } catch (JSONException ex) {
         throw new RuntimeException(ex);
       }
     }

     return jo;
   }

   /**
    * This is a helper method which converts the given {@link JSONArray} to a {@link List} of Strings.
    *
    * @param jsonStringArray The {@link JSONArray} to convert.
    * @return The converted {@link List} of Strings.
    */
   public static List<String> getStringsFromJSONArray(JSONArray jsonStringArray) throws JSONException
   {
     List<String> stringArray = Lists.newArrayListWithCapacity(jsonStringArray.length());

     for (int stringIndex = 0; stringIndex < jsonStringArray.length(); stringIndex++) {
       stringArray.add(jsonStringArray.getString(stringIndex));
     }

     return stringArray;
   }

   /**
    * This is a helper method which retrieves the schema tags from the {@link JSONObject} if they are present.
    *
    * @param jo The {@link JSONObject} to retrieve schema tags from.
    * @return A list containing the retrieved schema tags. The list is empty if there are no schema tags present.
    */
   public static List<String> getTags(JSONObject jo) throws JSONException
   {
     if (jo.has(FIELD_TAGS)) {
       return getStringsFromJSONArray(jo.getJSONArray(FIELD_TAGS));
     } else {
       return Collections.emptyList();
     }
   }

   private static final Logger LOG = LoggerFactory.getLogger(SchemaUtils.class);
 }
	/**
	* Licensed to the Apache Software Foundation (ASF) under one
	* or more contributor license agreements. See the NOTICE file
	* distributed with this work for additional information
	* regarding copyright ownership. The ASF licenses this file
	* to you under the Apache License, Version 2.0 (the
	* "License"); you may not use this file except in compliance
	* with the License. You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing,
	* software distributed under the License is distributed on an
	* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
	* KIND, either express or implied. See the License for the
	* specific language governing permissions and limitations
	* under the License.
	*/
	package org.apache.apex.malhar.lib.appdata.schemas;

	import java.io.IOException;
	import java.io.InputStream;
	import java.io.StringWriter;
	import java.util.Collection;
	import java.util.Collections;
	import java.util.Iterator;
	import java.util.List;
	import java.util.Map;
	import java.util.Set;

	import org.codehaus.jettison.json.JSONArray;
	import org.codehaus.jettison.json.JSONException;
	import org.codehaus.jettison.json.JSONObject;
	import org.slf4j.Logger;
	import org.slf4j.LoggerFactory;

	import org.apache.commons.io.IOUtils;

	import com.google.common.base.Preconditions;
	import com.google.common.collect.Lists;
	import com.google.common.collect.Maps;
	import com.google.common.collect.Sets;

	/**
	* This class holds utility methods for processing JSON.
	* @since 3.0.0
	*/
	public class SchemaUtils
	{
	public static final String FIELD_TAGS = "tags";

	/**
	* This constructor should not be used.
	*/
	private SchemaUtils()
	{
	//Do nothing
	}

	/**
	* This is a utility method which loads the contents of a resource file into a string.
	* @param resource The resource file whose contents need to be loaded.
	* @return The contents of the specified resource file.
	*/
	public static String jarResourceFileToString(String resource)
	{
	StringWriter stringWriter = new StringWriter();
	try {
	InputStream is = SchemaUtils.class.getClassLoader().getResourceAsStream(resource);
	Preconditions.checkArgument(is != null, resource + " could not be found in the resources.");

	IOUtils.copy(is, stringWriter);
	} catch (IOException ex) {
	throw new RuntimeException(ex);
	}
	return stringWriter.toString();
	}

	/**
	* This is a utility method that loads the contents of the given input stream into a string.
	* @param inputStream The input stream to read from.
	* @return The contents of the given input stream as a String.
	*/
	public static String inputStreamToString(InputStream inputStream)
	{
	StringWriter stringWriter = new StringWriter();

	try {
	IOUtils.copy(inputStream, stringWriter);
	} catch (IOException ex) {
	throw new RuntimeException(ex);
	}

	return stringWriter.toString();
	}

	/**
	* This is a utility method to check that the given JSONObject has the given keys.
	* @param jo The {@link JSONObject} to check.
	* @param fields The keys in the {@link JSONObject} to check.
	* @return True if the given {@link JSONObject} contains all the given keys. False otherwise.
	*/
	public static boolean checkValidKeys(JSONObject jo, Fields fields)
	{
	@SuppressWarnings("unchecked")
	Set<String> fieldSet = fields.getFields();
	Set<String> jsonKeys = getSetOfJSONKeys(jo);

	return jsonKeys.containsAll(fieldSet);
	}

	/**
	* This is a utility method to check that the given JSONObject has the given keys.
	* It throws an {@link IllegalArgumentException} if it doesn't contain all the given keys.
	* @param jo The {@link JSONObject} to check.
	* @param fields The keys in the {@link JSONObject} to check.
	*/
	public static void checkValidKeysEx(JSONObject jo, Fields fields)
	{
	@SuppressWarnings("unchecked")
	Set<String> fieldSet = fields.getFields();
	Set<String> jsonKeys = getSetOfJSONKeys(jo);

	if (!jsonKeys.containsAll(fieldSet)) {

	throw new IllegalArgumentException("The given set of keys " + fieldSet
	+ " doesn't equal the set of keys in the json " + jsonKeys);
	}
	}

	/**
	* This is a utility method to check that the given JSONObject has the given keys.
	* @param jo The {@link JSONObject} to check.
	* @param fieldsCollection The keys in the {@link JSONObject} to check.
	* @return True if the given {@link JSONObject} contains all the given keys. False otherwise.
	*/
	public static boolean checkValidKeys(JSONObject jo, Collection<Fields> fieldsCollection)
	{
	return checkValidKeysHelper(jo, fieldsCollection);
	}

	private static boolean checkValidKeysHelper(JSONObject jo, Collection<Fields> fieldsCollection)
	{
	for (Fields fields: fieldsCollection) {
	LOG.debug("Checking keys: {}", fields);
	if (checkValidKeys(jo, fields)) {
	return true;
	}
	}

	LOG.error("The first level of keys in the provided JSON {} do not match any of the " + "valid keysets {}",
	getSetOfJSONKeys(jo), fieldsCollection);
	return false;
	}

	public static boolean checkValidKeys(JSONObject jo, List<Fields> fieldsCollection)
	{
	return checkValidKeysHelper(jo, fieldsCollection);
	}

	/**
	* This is a utility method to check that the given JSONObject has the given keys.
	* It throws an {@link IllegalArgumentException} if it doesn't contain all the given keys.
	* @param jo The {@link JSONObject} to check.
	* @param fieldsCollection The keys in the {@link JSONObject} to check.
	* @return True if the given {@link JSONObject} contains all the given keys. False otherwise.
	*/
	public static boolean checkValidKeysEx(JSONObject jo, Collection<Fields> fieldsCollection)
	{
	return checkValidKeysExHelper(jo, fieldsCollection);
	}

	public static boolean checkValidKeysExHelper(JSONObject jo, Collection<Fields> fieldsCollection)
	{
	for (Fields fields: fieldsCollection) {
	if (checkValidKeys(jo, fields)) {
	return true;
	}
	}

	Set<String> keys = getSetOfJSONKeys(jo);

	throw new IllegalArgumentException("The given json object has an invalid set of keys: " + keys
	+ "\nOne of the following key combinations was expected:\n" + fieldsCollection);
	}

	public static boolean checkValidKeysEx(JSONObject jo, List<Fields> fieldsCollection)
	{
	return checkValidKeysExHelper(jo,
	fieldsCollection);
	}

	public static Set<String> getSetOfJSONKeys(JSONObject jo)
	{
	@SuppressWarnings("unchecked")
	Iterator<String> keyIterator = jo.keys();
	Set<String> keySet = Sets.newHashSet();

	while (keyIterator.hasNext()) {
	keySet.add(keyIterator.next());
	}

	return keySet;
	}

	public static Map<String, String> convertFieldToType(Map<String, Type> fieldToType)
	{
	Map<String, String> fieldToTypeString = Maps.newHashMap();

	for (Map.Entry<String, Type> entry : fieldToType.entrySet()) {
	String field = entry.getKey();
	String typeString = entry.getValue().name();

	fieldToTypeString.put(field, typeString);
	}

	return fieldToTypeString;
	}

	public static JSONArray findFirstKeyJSONArray(JSONObject jo, String key)
	{
	if (jo.has(key)) {
	try {
	JSONArray jsonArray = jo.getJSONArray(key);
	return jsonArray;
	} catch (JSONException ex) {
	throw new RuntimeException(ex);
	}
	}

	@SuppressWarnings("unchecked")
	Iterator<String> keyIterator = jo.keys();

	while (keyIterator.hasNext()) {
	String childKey = keyIterator.next();

	JSONArray childJa = null;

	try {
	childJa = jo.getJSONArray(childKey);
	} catch (JSONException ex) {
	//Do nothing
	}

	if (childJa != null) {
	JSONArray result = findFirstKeyJSONArray(childJa, key);

	if (result != null) {
	return result;
	}

	continue;
	}

	JSONObject childJo = null;

	try {
	childJo = jo.getJSONObject(childKey);
	} catch (JSONException ex) {
	//Do nothing
	}

	if (childJo != null) {
	JSONArray result = findFirstKeyJSONArray(childJo, key);

	if (result != null) {
	return result;
	}
	}
	}

	return null;
	}

	public static JSONArray findFirstKeyJSONArray(JSONArray ja, String key)
	{
	for (int index = 0; index < ja.length(); index++) {
	JSONArray childJa = null;

	try {
	childJa = ja.getJSONArray(index);
	} catch (JSONException ex) {
	//Do nothing
	}

	if (childJa != null) {
	JSONArray result = findFirstKeyJSONArray(childJa, key);

	if (result != null) {
	return result;
	}

	continue;
	}

	JSONObject childJo = null;

	try {
	childJo = ja.getJSONObject(index);
	} catch (JSONException ex) {
	//Do nothing
	}

	if (childJo != null) {
	JSONArray result = findFirstKeyJSONArray(childJo, key);

	if (result != null) {
	return result;
	}
	}
	}

	return null;
	}

	public static JSONObject findFirstKeyJSONObject(JSONObject jo, String key)
	{
	if (jo.has(key)) {
	try {
	JSONObject jsonObject = jo.getJSONObject(key);
	return jsonObject;
	} catch (JSONException ex) {
	throw new RuntimeException(ex);
	}
	}

	@SuppressWarnings("unchecked")
	Iterator<String> keyIterator = jo.keys();

	while (keyIterator.hasNext()) {
	String childKey = keyIterator.next();

	JSONArray childJa = null;

	try {
	childJa = jo.getJSONArray(childKey);
	} catch (JSONException ex) {
	//Do nothing
	}

	if (childJa != null) {
	JSONObject result = findFirstKeyJSONObject(childJa, key);

	if (result != null) {
	return result;
	}

	continue;
	}

	JSONObject childJo = null;

	try {
	childJo = jo.getJSONObject(childKey);
	} catch (JSONException ex) {
	//Do nothing
	}

	if (childJo != null) {
	JSONObject result = findFirstKeyJSONObject(childJo, key);

	if (result != null) {
	return result;
	}
	}
	}

	return null;
	}

	public static JSONObject findFirstKeyJSONObject(JSONArray ja, String key)
	{
	for (int index = 0; index < ja.length(); index++) {
	JSONArray childJa = null;

	try {
	childJa = ja.getJSONArray(index);
	} catch (JSONException ex) {
	//Do nothing
	}

	if (childJa != null) {
	JSONObject result = findFirstKeyJSONObject(childJa, key);

	if (result != null) {
	return result;
	}

	continue;
	}

	JSONObject childJo = null;

	try {
	childJo = ja.getJSONObject(index);
	} catch (JSONException ex) {
	//Do nothing
	}

	if (childJo != null) {
	JSONObject result = findFirstKeyJSONObject(childJo, key);

	if (result != null) {
	return result;
	}
	}
	}

	return null;
	}

	/**
	* Converts the given JSONObject into a {@link Map}.
	* @param jo The {@link JSONObject} to convert.
	* @return The converted {@link JSONObject}.
	*/
	public static Map<String, String> extractMap(JSONObject jo)
	{
	Map<String, String> resultMap = Maps.newHashMap();
	@SuppressWarnings("unchecked")
	Iterator<String> keyIterator = jo.keys();

	while (keyIterator.hasNext()) {
	String key = keyIterator.next();
	String value;

	try {
	value = jo.getString(key);
	} catch (JSONException ex) {
	throw new RuntimeException(ex);
	}

	resultMap.put(key, value);
	}

	return resultMap;
	}

	/**
	* This is a utility method which creates a {@link JSONObject} out of the given map.
	* @param map The map to convert into a {@link JSONObject}.
	* @return The converted map.
	*/
	public static JSONObject createJSONObject(Map<String, String> map)
	{
	JSONObject jo = new JSONObject();

	for (Map.Entry<String, String> entry : map.entrySet()) {
	String key = entry.getKey();
	String value = entry.getValue();

	try {
	jo.put(key, value);
	} catch (JSONException ex) {
	throw new RuntimeException(ex);
	}
	}

	return jo;
	}

	/**
	* This is a helper method which converts the given {@link JSONArray} to a {@link List} of Strings.
	*
	* @param jsonStringArray The {@link JSONArray} to convert.
	* @return The converted {@link List} of Strings.
	*/
	public static List<String> getStringsFromJSONArray(JSONArray jsonStringArray) throws JSONException
	{
	List<String> stringArray = Lists.newArrayListWithCapacity(jsonStringArray.length());

	for (int stringIndex = 0; stringIndex < jsonStringArray.length(); stringIndex++) {
	stringArray.add(jsonStringArray.getString(stringIndex));
	}

	return stringArray;
	}

	/**
	* This is a helper method which retrieves the schema tags from the {@link JSONObject} if they are present.
	*
	* @param jo The {@link JSONObject} to retrieve schema tags from.
	* @return A list containing the retrieved schema tags. The list is empty if there are no schema tags present.
	*/
	public static List<String> getTags(JSONObject jo) throws JSONException
	{
	if (jo.has(FIELD_TAGS)) {
	return getStringsFromJSONArray(jo.getJSONArray(FIELD_TAGS));
	} else {
	return Collections.emptyList();
	}
	}

	private static final Logger LOG = LoggerFactory.getLogger(SchemaUtils.class);
	}